Rotating cylinder positioning mechanism



June 13, 1961 F. A. LITZ 2,988,057

ROTATING CYLINDER POSITIONING MECHANISM Filed Feb 6, 1958 5 Sheets-Sheet 1 INVENTOR. FRANK A. L/TZ BY QMEM ATTORNEY June 13, 1961 Filed Feb. 6, 1958 F. A. LITZ ROTATING CYLINDER POSITIONING MECHANISM June 13, 1961 F. A. LITZ ROTATING CYLINDER POSITIONING MECHANISM 3 Sheets-Sheet 5 Filed Feb. 6, 1958 WN RN Unite This invention relates in general to positioning mechanisms and in particular to an improved mechanism for discretely position-ing a member in response to signals representative of digital information.

Various types of mechanisms for positioning a member in response to signals corresponding to digital information have been suggested in the prior art. Such mechanisms may be conveniently classified into two general classes, namely, those which operate on the principle of summing the rectilinear displacements of a plurality of pistons or cylinders, and those which operate on the principle of summing the angular displacements of a plurality of rotating members. The latter class of mechanisms has the main advantage of being more compact when compared with the first class. However, the rotary type mechanisms disclosed in the prior art usually require more elaborate control devices such as differential pressure valves and different sources of pressure for satisfactory operation. It has been found in accordance with the present invention that a rotating member positioning mechanism may be constructed which employs only a single pressure source and simple valves, thus resulting in a simple, economical and compact arrangement. The improved mechanism comprises generally a plurality of rotating cylinder units connected in series to produce an analog output in response to digital informational signals. Each unit comprises a cylindrical housing block provided with a pair of housing ports, a cylinder rotatably mounted in the housing block and provided with a pair of circumferentially disposed, continuous port grooves communicating with the housing ports and a pair of radially extending, angularly spaced ports extending between the inside of the cylinder and the continuous port grooves, a shaft mounted for controlled rotational movement relative to a sector member fixedly mounted within the rotating cylinder, a vane member fixed to the shaft so as to rotate between the angularly spaced ports, and valve means for supplying fluid pressure through each series of ports selectivelyto either side of the rotating vane. The shaft of each unit is connected to the rotating cylinder of the next succeeding unit so that the angular position of the last shaft represents the summation of the angular movements of all the preceding shafts. A relatively compact positioning mechanism operable from a single source of pressure is thus obtained.

It is therefore an object of the present invention to provide an improved pressure responsive positioning mechanism.

Another object of the present invention is to provide a positioning mechanism employing a plurality of rotating members which is operable from a single pressure source.

A further object of the present invention is to provide a positioning mechanism of the rotary vane type which may be controlled by simple valves.

A still further object of the present invention is to provide an improved digital-to-analog converter.

A still further object of the present invention is to pro vide a pressure responsive mechanism for discretely positioning a member at a preselected one of a plurality of angularly spaced positions.

Other objects of the invention will be pointed out in the following description and claims and illustrated in States Patent 2 the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode which has been contemplated of applying that principle.

In the drawings:

FIG. 1 is a perspective view, partly in section illus-' trating a rotating member type positioning mechanism embodying the present invention.

FIG. 2 is an exploded view, partly in section, of one of the rotating cylinder units shown in FIG. 1.

FIG. 3 is a sectional view of the rotating cylinder unit shown in FIG. 2 in the assembled state.

FIG. 4 is a view in section taken along the line IVIV in FIG. 3.

FIG. 5 is a view in section taken along the line V-V of a group of valves 14a through 14d, each of which is associated with a different one of the rotating cylinder units 11. The rotating cylinder units are substantially identical and hence only one is described in detail.

As shown in FIG. 2, each unitv comprises a rotating cylinder housing 16 provided with a pair of ports 17 and 18, a rotating cylinder 19 provided with a pair of axially spaced, circumferentially disposed, continuous port grooves 20 and 21 and a pair of radially disposed angularly spaced passages 22 and 23 which extend in wardly from each groove and intersect the inner wall 24 of the cylinder at arcuately spaced points. Rotating cylinder 19 is positioned within the housing 16 for rotational movement on an axis so that the circumferentially disposed, continuous port grooves 20 and 21 register respectively with a pair of ports 17 and 18 in the housing regardless of the angular position of the cylinder 19. Each unit further includes a cylinder sector 26 disposed coaxially with the rotating cylinder 19 and provided with a pin element 27 which engages a hole 28 disposed in an inner shoulder portion 29 of the rotating cylinder 19, thus causing the sector 26 to rotate with the cylinder 19. The sector and cylinder may be made integral but for manufacturing purposes and other reasons which will become obvious, they are preferably made as separate elements.

Cylinder sector 26 is provided with a pair of shoulder stops 30 and 31 which define the angular movement of a rotary vane member 33 relative to the rotating cylinder 19. The shoulder stops 30 and 31 are disposed at substantially the same angular spacing as the radially extending ports 22 and 23 in the rotating cylinder 19. The rotary vane member 33 is fixedly attached to a shaft 34 whichis journaled in the sector 26, the distal end 36 of the shaft 34 extending outside of the unit 11 through a suitable cover plate 37. End 36, as shown, connects directly to the rotating cylinder of the next succeeding unit by means of a set screw 39. However, the connection may be made through a universal joint, if desired. The distal end 36 of the shaft 34d of the last unit may be connected to the indicator 12, as shown in FIG. 1, or to any suitable motion transmitting means.

The operation of the rotating cylinder units may be seen by reference to FIGS. 4 and 5 which are sectional views taken along the lines IVIV and V'V of FIG. 3.

is only necessary to reverse the fluid pressure connections to the ports 17 and 18 in the rotating cylinder housing 16. Such a condition is represented in FIG. where the vane has been moved. to, its extreme left-hand position, fluid pressure being applied to the right-hand surface of the vane through the series of ports 18, 21 and 23. It will be noted that the extent of angular movement of the vane 33 is determined by the angular displacement of the shoulder stops 30 and 3-1 on the cylinder sector 26. It is therefore possible to provide each unit 11 with a cylindri-, cal sector 26 whose shoulder stops 30 and 31 are spaced angularly in accordance with some predetermined arrangement. For example, the mechanism may be conveniently arranged to convert digital information coded in the conventional well known binary numbering system into analog information merely by having each sector 26 correspond to a different order of the binary numbering system. Thus, in the mechanism shown in FIG. 1 the cylindrical sector 26 of the first unit 11a would have an angular spacing of one unit (which maybe five degrees), the second sector 2611 an angular spacing of two units, the following sector 26c an angular spacing of four units, and the last sector 26d an angular spacing of eight units.

Since the rotating cylinders of each unit are coupled together, their individual angular movements are cumulative, thereby causing the indicator 12 to be positioned in accordance with the operation of the individual rotating cylinder units 11.

, It should be noted that the movement of the vanes 33 may be throttled or dampened by controlling the shape of the radially extending ports 22 and 23 on the inner cylindrical surface 24 of the rotating cylinder 19.

Suitable means for controlling the selective application of pressure to each of the vanes 36 is also provided. As shown in FIG. 1, this means comprises a valve block 40,

the plurality of solenoid operated valves 14a through 14d.

mounted in the block and associated with the respective units 11a through 11d, a valve block cover 41, and a source of pressure 43, either hydraulic or pneumatic,.rep-' angular analog displacement of the output shaft 34d of the last unit 11d is obtained. A

While there have b'enfshown and described and pointed out the fundamental novel features of the invention as applied to .the preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details. of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the..intention, therefore, to be limited only as indicated by. the scope of the following claims. v

What is claimed is: e V p l. A unit for a pressure responsive positioning mechanism comprising in combination ahousing block, a cylindrical member mounted in said housing block for rotational movement on an axis and provided with a single sector-shaped internal bore, a shaft disposed coaxially with said cylindrical member and mounted for rotational movement relative thereto, a single vane member fixed to said shaft and extending radially therefrom to the curved surface defining said sector-shaped bore to form two pressurable cavities, and means for'supplying pressure selectivelyto said cavitiesto rotate said shaft through an angle defined by said sector-shaped bore, said pressure supply means including first and second fluid paths each of which extendsfrom one of said pressurable cavities through a' cylindrical wall portion of said cylindrical member and through said housingfblock.-

2. The invention recited in claim 1 in which each said fluid path comprises aport disposed in said housing block. a circumferentially disposed continuous groove disposed in said cylindrical member in registry with said housing port, and a channel extending radially outward from said one said cavity through said wall portion to said continu- V ous groove.

through a channel 46 in the valve block, through the left inlet section 47 of the valve, through the left housing port 17 (see FIG. 4), through the continuous port groove 20 in the rotating cylinder 19, through the radially extending port 22 to the left side of the vane '33. The return fluid path extends from the right side of the vane, through the radially extending port 23 to the continuous port groove 21, through the right housing port 18, through the return section 48 of the valve 14 to the return channel 51) in the valve block 40 and then to the return conduit 45.

Corresponding paths are set up when the valve 14 is moved to its other position illustrated in FIG. 7 so that the rotating vane 33 is moved counterclockwise as viewed in FIGS. 1, 2 and 5.

In the preferred embodiment illustrated in FIG. 1, the valves 14 are operated by solenoids 51 which may be energized through suitable means shown diagrammatically as battery 52 and a switch 53. Energizing of the solenoid 51 causes the valve to move from the position shown in FIG. 6 to that shown in FIG. 7, which results in the rotating vane 83 of the associated rotating cylinder unit to be moved from a zero position shown in FIG. 4 to the one position shown in FIG. 5. If solenoid 51a is ener- 3. The invention recited in claim 2Wherein, each of said radially extending channels intersects the curved surface of said sector-shaped bore at points which have an arcuate spacing determined by said bore.

4. The inventionv recited in claim 2 wherein said radially extending channels are arcuately spaced in accordance with the anglesubtended by said sector-shaped bore.

5. The invention recited in claim 2 wherein said circumferentially disposed continuous grooves of said first and second paths are axially spaced.

References Cited in the tile of this patent UNITED STATES-PATENTS 657,113 Holm Sept. 4, 1900 2,304,894 Dilworth Dec. 15, 1942 2,374,588 I Doran a Apr. 24, 1945 2,384,218. Tucker 1- Sept. 4, 1945' 2,443,333 Tucker June 15, 1948 2,811,141 Van Coney et al. Oct. 29, 1957 2,825,307 Enyeart et al. p Mar. 4, 1958 2,870,748 Hemphill Ian. 27, 1959 2,902,009 Ludwig et al Sept. 1, 1959 2,911,956 Smith 1 Nov. 10, 1959 2,915,044 Nelson Dec. 1, 1959 FOREIGN PATENTS 1,010,584" France "1'... Mar. 26, 1952 917,585 Germany Sept. 6, 1954 

